The present invention generally relates to a recording system and more particularly, to a double-side or both surface recording system (referred to as a both surface recording system hereinbelow) arranged to form and record required images on both surfaces of each sheet such as a copy paper sheet, by a recording apparatus having an image forming section for forming and recording the image on one surface of the sheet.
Conventionally, in a copying apparatus and the like, there have been proposed, for example, in U.S. Pat. No. 4,098,551 (Komori et al., patented July 4, 1978), a system arranged to form and record images on opposite or both surfaces of one sheet. This known system is so arranged that, with an intermediate tray being disposed between a paper feed cassette and a paper discharge tray, a large number of sheets fed from a paper feed section to an image forming section, and each having an image formed and recorded on its one surface, are once stacked on the intermediate tray for storing, and after completion of the recording on the surfaces thereof, the sheets thus accommodated on the intermediate tray are fed back again to the image forming section so as to effect image formation and recording on their reverse surfaces for carrying out the both surface recording.
In the conventional arrangement described above, however, the apparatus tends to be large in size, since the intermediate tray must be disposed between the paper feed cassette and the paper discharge tray for effecting the both face recording. Moreover, between the respective sheets after the surface recording and stacked on the intermediate tray, an electrostatic attracting force arising from corona charging in a transfer process during the surface recording is exerted, and therefore, during delivery of the sheets after the surface recording, from the intermediate tray one sheet by one sheet through feeding rollers, there is a possibility that the sheets are undesirably piled one upon another, and thus, two or more sheets are forwarded at the same time. Accordingly, some means for sufficiently erasing the charge on the sheets stacked on the intermediate tray is required, thus resulting in a further increase in the size of the apparatus on the whole.
Moreover, after once being stacked for storage on the intermediate tray, the sheets after the one or front surface recording are successively fed out, one sheet by one sheet, from either the top or bottom of the stack for being subjected to image formation on the remaining reverse surfaces thereof, and thus, sequence control for the both surface recording becomes undesirably complicated, while simultaneously, a loss in time may result during change-over between the recording for the front surface and the recording for the reverse surface.
Furthermore, since pressure is applied by the feeding rollers, with respect to the sheets formed and recorded with the image on the front surfaces, and stacked on the intermediate tray, there may arise such a disadvantage that the reverse surface of each sheet at the pressurized portion is soiled by the image formed on the front surface of a subsequent sheet located thereunder in the stack.